Pararenal stent graft

ABSTRACT

A stent graft for endovascular introduction into the pararenal region of the descending aorta. The stent graft has an elongate tubular body ( 10 ) with a proximal portion ( 12 ), a distal portion ( 16 ) of a diameter less than the proximal portion and a tapered central portion ( 14 ). A notional transverse clock face on the tubular body has 12 o&#39;clock at a notional anterior longitudinal datum line. The stent graft has a scalloped cut out ( 26 ) centered at about 12:30 o&#39;clock and a fenestration ( 28 ) at about 12:00 o&#39;clock in the proximal portion and first and second fenestration assemblies which can be low profile side arms at about 2:15 o&#39;clock and about 10:00 o&#39;clock in the tapered central portion. The tapered central portion can have an arcuate side wall ( 30 ) so that the tapered portion has an outer face which is concave.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of provisional application Ser. No.61/211,308 filed Mar. 26, 2009.

TECHNICAL FIELD

This disclosure relates to a medical device and more particularly to amedical device for endovascular deployment into the aorta of a patient.

BACKGROUND OF THE INVENTION

This disclosure relates to a stent graft for endovascular deploymentinto the descending aorta of a patient to treat arterial disease such asan aneurism. An aneurysm can extend to the para-renal or supra-renalregion of the descending aorta and hence to obtaining good proximal sealit may be necessary to deploy a stent graft which could potentiallycover one or more of the branch vessels of the descending aorta in thatregion.

In the descending aorta there are a number of branch vessels which it isimportant not to occlude during the placement of a stent graft into thedescending aorta to span an aneurism or the like. These vessels includethe superior mesenteric artery, the celiac artery and the renalarteries.

The relative position of these arteries can vary considerably frompatient to patient and hence it has often been necessary to manufacturea custom made device to fit a particular vasculature.

Throughout this specification the term distal with respect to a portionof the aorta, a deployment device or a prosthesis means the end of theaorta, deployment device or prosthesis further away in the direction ofblood flow away from the heart and the term proximal means the portionof the aorta, deployment device or end of the prosthesis nearer to theheart. When applied to other vessels similar terms such as caudal andcranial should be understood.

Throughout this discussion the term “stent graft” is intended to mean adevice which has a tubular body of biocompatible graft material and atleast one stent fastened to the tubular body to define a lumen throughthe stent graft. The stent graft may be bifurcated and havefenestrations, side arms or the like. Other arrangements of stent graftsare also within the scope of the disclosure.

SUMMARY OF THE INVENTION

It is the object of this disclosure to provide a stent graft which canbe used as an off the shelf device for a wide range as possible ofvariations in positions of the vessels in the descending aorta andthereby enabling treatment of as many patients as possible.

In one form therefore, although this may not necessarily be the only orbroadest form, the disclosure is said to reside in a stent graftcomprising an elongate tubular body of a biocompatible graft material,the tubular body comprising a distal end and a proximal end, the tubularbody comprising a proximal portion of a first selected diameter, adistal portion of a second selected diameter, the second selecteddiameter being less than the first selected diameter and a taperedcentral portion between the proximal portion and the distal portion, thetubular body comprising a circumference, a notional anteriorlongitudinal datum line on the tubular body and a notional transverseclock face having 12 o'clock at the notional anterior longitudinal datumline;

a scalloped cut out in the proximal portion of the tubular body, thescalloped cut out being open at the proximal end of the tubular body;

a fenestration in the proximal portion, the fenestration being distal ofthe scalloped cut out;

first and second fenestration assemblies in the distal end of thetapered central portion,

the scalloped cut out being circumferentially centered with respect tothe notional transverse clock face at 12:30 o'clock, the fenestration inthe proximal portion being circumferentially centered with respect tothe notional transverse clock face at 12:00 o'clock, the firstfenestration assembly arm being circumferentially centered with respectto the notional transverse clock face at 2:15 o'clock and the secondfenestration assembly being circumferentially centered with respect tothe notional transverse clock face at 10:00 o'clock.

Preferably there are a plurality of self expanding stents affixed alongthe tubular body and an exposed zig zag self expanding stent extendingfrom the proximal end of the proximal portion.

Preferably the tapered portion comprises an arcuate side wall wherebythe tapered portion comprises an outer face which is concave.

Preferably the first and second fenestration assemblies each compriselow profile side arms, the low profile side arms each comprising aproximal external open end.

Preferably the first and second low profile side arms each comprise atubular side branch sealingly received into a side arm fenestrationwherein an inner portion of the tubular side branch extends within thetubular body and an outer portion of the tubular side branch extendsexteriorly of the tubular body and such that the tubular side branchextends from the tubular body at an angle thereto and each of the lowprofile side arms comprise an external open end facing proximally.

Preferably each tubular side branch comprises a reinforcement stent andwherein the reinforcement stent comprises a portion of wire forming afirst ring and a second ring, the second ring defining a plane which issubstantially parallel to and spaced axially apart from the plane of thefirst ring and at least one wire portion extending between the first andsecond ring.

Preferably the stent graft comprises an overall length of approximately100 to 120 mm and preferably 111 mm, the first selected diameter of theproximal portion being 26 to 42 mm and preferably 30 mm, the secondselected diameter of the distal portion being 20 to 30 mm and preferably20 mm, the proximal portion comprising a longitudinal length of 35 to 45mm, the distal portion comprising a longitudinal length of from 45 to 55mm, the tapered portion comprising a longitudinal length ofapproximately 15 to 25 mm, the scalloped cut out comprising acircumferential width of about 20 mm and a longitudinal depth of about19 mm, the fenestration comprising a diameter of about 8 mm and beingcentered at a distance of approximately 26 mm from the proximal end andthe proximal openings of the first and second low profile side arms eachbeing centered at a distance of approximately 55 mm from the proximalend.

Preferably the proximal portion of the tubular body comprises aproximally extending bare attachment stent and first and second selfexpanding stents spaced apart longitudinally, the tapered centralportion comprises a single self expanding stent and the distal portioncomprises a plurality of self expanding stents.

In a preferred embodiment each of the second stent of the proximalportion and the single self expanding stent of the tapered centralportion comprise a asymmetric self expanding zig zag stent, theasymmetric self expanding zig zag stent comprising a plurality of strutsand proximal and distal bends between the struts and a circumference anda part of the circumference comprising bends being spacedcircumferentially further apart than others of the bends, therebydefining wider void regions between the bends which are spacedcircumferentially further apart.

In a preferred embodiment the asymmetric self expanding zig zag stentcomprising the second stent of the proximal portion is positioned suchthat the part of the circumference comprising bends being spaced furtherapart is in the posterior region of the stent graft and the afenestration in the proximal portion is in a wider void region.

In a preferred embodiment the asymmetric self expanding zig zag stentcomprising the single self expanding stent of the tapered centralportion is affixed to the stent graft such that the part of thecircumference comprising bends being spaced further apart is in theposterior region of the stent graft and the void regions arelongitudinally proximal of the open external ends of the first andsecond low profile side arms.

Alternatively the tapered central portion comprises a asymmetric selfexpanding zig zag stent, the asymmetric self expanding zig zag stentcomprising a plurality of struts and proximal and distal bends betweenthe struts and a circumference and a part of the circumferencecomprising bends being spaced circumferentially further apart thanothers of the bends, thereby defining wider void regions between thebends which are spaced circumferentially further apart, the asymmetricself expanding zig zag stent being affixed to the stent graft such thatthe part of the circumference comprising bends being spaced furtherapart is in the posterior region of the stent graft and the void regionsare longitudinally proximal of the open external ends of the first andsecond low profile side arms.

Preferably each of the tubular side branches are mounted into thetapered portion by being stitched to the tubular body, the stitchingextending circumferentially and diagonally from a proximal end of thetubular side branch to a distal end of the tubular side branch such thatthe tubular side branch extends from the tubular body at an anglethereto.

It will be seen that by this disclosure there is provided a stent graftwhich can be deployed into the vasculature of a patient using knownSeldinger techniques and placed such that the superior mesenteric arteryis accessible through the fenestration in the proximal portion, thescalloped cut-out in the proximal portion allows access to the celiacartery and side branch stents can be deployed through each of the firstand second low profile side arms to extend to the left and right renalarteries.

The applicant has studied the positions of these arteries in a largenumber of patient and determined optimal positions for each of thescalloped fenestrations and the side arms to enable access to therespective side branches in as many patients as possible. This enablesan off the shelf device to be devised according to the presentdisclosure.

BRIEF DESCRIPTION OF THE DRAWING

This then generally describes the disclosure but to assist withunderstanding reference will now be made to the accompanying drawingswhich show a preferred embodiment of the disclosure.

In the Drawings:

FIG. 1 shows a side view of a stent graft according to preferredembodiment of the present disclosure;

FIG. 2 shows a schematic bottom view of the stent graft according to thepresent disclosure showing the notional clock-face and relativepositions of the scalloped cut out, the fenestration and the side arms;

FIG. 3 shows a part cross-sectional view of the stent graft, inparticular showing the outer concave surface of the tapered portion;

FIG. 4 shows a stent arrangement suitable for the low profile side arm;

FIG. 5 shows a low profile side arm suitable for the present disclosure;

FIG. 6 shows an asymmetric stent useful for the tapered portion andsecond stent of the stent graft of the present disclosure; and

FIG. 7 shows a schematic view of a stent graft of the present disclosureparticularly showing relevant dimensions.

DETAILED DESCRIPTION

In FIG. 1 a stent graft 10 according to one embodiment of the presentdisclosure comprises a tubular body which has three notional sections.The three notional sections comprise a proximal tubular body section 12,a tapered central tubular body portion 14 and a distal tubular bodyportion 16. Each of the proximal tubular body section 12, the taperedcentral tubular body portion 14 and the distal tubular body portion 16are substantially concentric and in fluid communication with each other.

The tubular body comprises of a biocompatible graft material. Thebiocompatible graft material can include polytetrafluoroethylene,dacron, polyamide or any other suitable biocompatible graft material.

While DACRON, expanded polytetrafluoroethylene (ePTFE), or othersynthetic biocompatible materials can be used for the tubular graftmaterial for the stent graft, a naturally occurring biomaterial, such ascollagen, is highly desirable, particularly a specially derived collagenmaterial known as an extracellular matrix (ECM), such as smallintestinal submucosa (SIS). Besides SIS, examples of ECM's includepericardium, stomach submucosa, liver basement membrane, urinary bladdersubmucosa, tissue mucosa, and dura mater.

SIS is particularly useful, and can be made in the fashion described inBadylak et al., U.S. Pat. No. 4,902,508; Intestinal Collagen Layerdescribed in U.S. Pat. No. 5,733,337 to Carr and in 17 NatureBiotechnology 1083 (Nov. 1999); Cook et al., WIPO Publication WO98/22158, dated 28 May 1998, which is the published application ofPCT/US97/14855, the teachings of which are incorporated herein byreference. Irrespective of the origin of the material (synthetic versusnaturally occurring), the material can be made thicker by makingmultilaminate constructs, for example SIS constructs as described inU.S. Pat. Nos. 5,968,096; 5,955,110; 5,885,619; and 5,711,969. Inaddition to xenogenic biomaterials, such as SIS, autologous tissue canbe harvested as well, for use in forming the tubular graft material.Additionally Elastin or Elastin-Like Polypetides (ELPs) and the likeoffer potential as a material to fabricate the tubular graft material toform a device with exceptional biocompatibility. SIS is available fromCook Biotech, West Lafayette, Ind., USA.

The tubular body is supported by a plurality of self expanding stentswhich are mounted either inside or outside of the tubular body. Thestents comprise a proximal stent 22, a stent 24 distal of the proximalstent in the proximal portion, a stent 32 in the tapered central portionand stents 38 in the distal portion. An exposed proximal stent 20extends proximally of the proximal end of the tubular body. The stents24 and 32 are asymmetric stents. The specific construction of the stents24 and 32 will be discussed below.

The stents 22 and 24 are mounted inside the tubular body to give asmooth outside sealing surface. The placement of the stent 32 in thetapered central; portion will be discussed below.

The stents may be constructed from stainless steel, nitinol which is anickel titanium alloy or any other suitable material.

The proximal portion 12 comprises a tube of substantially constantdiameter. The proximal portion 12 also has a scalloped cut out orfenestration 26 and a further substantially circular fenestration 28.The scalloped fenestration 26 is open to the proximal end of the stentgraft and a number of the struts 22 a of the proximal stent 22 extendbare across the scalloped fenestration 26. The fenestration 28 is placedsubstantially between the stent 22 and the stent 24. The relativecircumferential positions of scalloped fenestration 26 and thefenestration 28 will be discussed below.

Two low profile side arms 34 and 36 are mounted into the tapered centralportion 14 with their external open ends 34 a and 36 a extendingproximally. As can be seen in FIG. 3, the low profile side arm ismounted at an angle to the wall of the stent and the open end of the lowprofile side arm 34 b within the stent graft extends towards the distalend of the stent graft.

The two low profile side arms 34 and 36 are mounted into the taperedcentral portion 14 with stitching or other fastening 35 (see FIG. 3)extending diagonally on the low profile side arms 34 and 36 from one endto the other. Hence the stitching 35 by which the low profile side arms34 and 36 mounted and sealed into the tapered portion 14 extendscircumferentially and diagonally from the proximal end of the sidebranch to the distal end of the side branch such that the side branchextends from the tubular body at an angle thereto.

The tapered central portion 14 has an arcuate wall 30 as best can beseen in FIG. 3. The arcuate wall 30 presents a concave outer surface ofthe tapered portion 14. The tapered central portion is supported by anasymmetric stent 32. The configuration of the asymmetric stent 32 willbe discussed in relation to FIG. 6. The arcuate wall 30 allows a sidebranch stent 31 (shown dotted in FIG. 3) to extend from the low profileside arm and to curve over to a side branch vessel such as a renalartery without deleteriously engaging the arcuate wall 30 which maycause the side arm stent to be partially closed off and thereby restrictblood flow to the branch vessel.

The distal portion of the stent graft 16 comprises a tubular body ofsubstantially constant diameter with two or more stents 38 supportingit. These stents in the distal portion can be inside or outside of thetubular body depending upon the extension pieces which may be used toextend further down the aorta. Such an extension piece may be abifurcated stent graft with legs for each of the iliac arteries or anaorto-uni-iliac stent graft. Placement of the stents on the inside oroutside of the distal portion also dependent upon whether the stentgraft of the present disclosure is to be deployed first and a distalextension mounted later in which case it is preferable to leave theinterior surface of the distal portion smooth for good sealing and placethe stents on the outside. Otherwise the stents will be placed on theinside and a distal extension be deployed first.

A notional anterior longitudinal datum line 40 can be imagined on thestent graft and anterior markers 42 placed along the notionallongitudinal datum line. Posterior markers 44 can also be placed ontothe tubular body of the stent graft and when the markers are aligned asshown in FIG. 1 during deployment of the stent graft the correctposition of the stent graft can be visualized.

FIG. 2 shows a schematic representation of the stent graft from below.For clarity the stents have not been included. A notional clock-face hasbeen superimposed upon the schematic stent graft with twelve o'clockpositioned on the notional anterior longitudinal datum 40. Theclock-face has a twelve o'clock position 50, a three o'clock position52, a six o'clock position 54 and a nine o'clock position 56. Thereinforced scallop 26 is positioned so that its centre 26 a is at thetwelve-thirty o'clock position of the notional clock-face. Thefenestration 28 is positioned at the twelve o'clock position 50 of theclock-face. The first low-profile side arm 36 is positioned so that itscentre is at two-fifteen o'clock 36 c of the notional clock-face and thesecond low-profile side arm 34 is positioned at the ten o'clock position34 c of the notional clockface.

As an alternative indication of the respective positions of thefenestrations and side arms with respect to the notional anteriorlongitudinal datum 40 a measurement based upon degrees can be used. Bythis system the reinforced scallop 26 can be positioned so that it iscentered at about 15 degrees from the notional anterior datum line, thefenestration 28 is at about 0 degrees, the first low-profile side arm 34is positioned at about 67 degrees and the second low-profile side arm 36is positioned at approximately 300 degrees. All of these anglemeasurements are made clockwise from the notional anterior line whenviewed from the distal end of the stent graft.

FIG. 3 shows a part cross-sectional view of the stent graft shown inFIG. 1 and in particular showing the concave surface of the taperedportion. The wall of the stent graft 10 in the region of the taperedcentral portion 14 presents a concave outer surface for the reasons asdiscussed above. In can also be noted in FIG. 3 the diagonal stitching35 extending circumferentially and diagonally from a proximal end of thetubular side branch 34 a to a distal end of the tubular side branch 34 bsuch that the tubular side branch extends from the tubular body at anangle thereto.

FIG. 4 shows a view of two resilient wire ring and strut assemblies usedtogether to form a reinforcement stent 60 used on the low profile sidearm and FIG. 5 shows a view of a low profile side arm constructed usingthe stent shown in FIG. 4. In this embodiment the stent 60 comprisesupper and lower ring and strut assemblies 62 and 64 formed fromrespective rings 62 a and 64 a and longitudinal struts 62 b and 64 b.The stent is formed from two piece of nitinol or similar wire and thewires terminate in loops 68 and 69.

FIG. 5 shows a detailed view of a tubular side branch using the stentshown in FIG. 4. The tubular side branch 70 comprises a tubular portionof biocompatible graft material 72 with the stent 60 outside of it sothat the ring 62 a is at one end of the tubular body and the ring 64 ais at the other end of the tubular body and the strut 62 b extends alongthe outside of the tubular body. The ring and strut assemblies 62 and 64are stitched to the tubular body by stitching 74 and 76.

FIG. 6 shows a stent 80 suitable for the asymmetric stents 32 and 24used in the proximal and tapered portion of the stent graft 10 shown inFIG. 1. The stent 80 comprises a plurality of struts 82 and proximalbends 86 and distal bends 84 between the struts 82. The stent 80 isformed in a substantially planar form and then formed into a cylindricalform as illustrated with a notional cylindrical circumference 88. Wherethe ends of the planar form meet there is an overlap of struts. When thestent is mounted onto the wall of the stent graft by stitching (notshown) the stent is retained in its frustoconical form as shown in FIG.1 when it is mounted into the tapered central portion and is in acylindrical form when it is mounted inside the proximal portion.

Around a part of the circumference 88 of the asymmetric stent 80 theproximal bends 86 a and distal bends 84 a are spaced further apart thanin other parts of the circumference. In use the asymmetric selfexpanding zig zag stent 80 is affixed to the stent graft such that thepart of the circumference comprising the bends being spaced furtherapart is in the posterior region of the graft. In the proximal regionthis gives a region suitable for placement of the fenestration 28. Theasymmetric stent 32 is placed inside the tubular graft material in thetapered central region so that struts do not interfere with placement ofa side arm. In the tapered central region the placement of theasymmetric stent also defines void regions 14 a between the adjacentwider spaced struts immediately above to openings of the tubular sidearms. This prevents a strut engaging a side arm in that region andpossibly occluding the side arm in use.

FIG. 7 shows a schematic view of a stent graft of the present disclosureparticularly showing relevant dimensions. Where there is a dimensionrange given the preferred dimension is given in parentheses. In thisembodiment the overall length of the stent graft less the length of theexposed stent can range from 100 to 120 mm. It is preferably 111 mm. Thelength of the proximal portion 12 can range from 35 to 45 mm and ispreferably 39 mm. The length of the tapered portion can range from 15 to25 mm and is preferably 18 mm. The length of the distal portion 16 canrange from 45 to 55 mm and is preferably 54 mm. The diameter of theproximal portion 12 can range from 26 to 42 mm and the diameter of thedistal portion 16 can range from 20 to 30 mm.

The proximal scalloped cut out 26 preferably has a circumferential widthof 15 to 25 mm and preferably 20 mm. It has a longitudinal depth of 15to 25 mm and preferably 20 mm. The fenestration 28 preferably has adiameter of 8 mm and its centre is at a longitudinal position of 26 mmfrom the proximal end of the stent graft. The proximal open ends 34 aand 36 a of the first and second low profile side arms 34, 36 arepreferably spaced 55 mm from the proximal end of the stent graft.

As discussed above the preferred dimensions are the result of carefulanalysis of the vasculature of a large number of patients to provide a“off the shelf” device which will fit as many patients as possible.

In use the stent graft is introduced into the human body so that thefenestration 28 allows fluid access from the lumen of the stent graft tothe superior mesenteric artery. The celiac artery would then be in theregion of the scalloped cut out thereby allowing fluid access to thatvessel. Side branch stents can then be deployed from each of the firstand second low profile side arms 34, 36 to allow access to the renalarteries.

Throughout this specification various indications have been given as tothe scope of the disclosure, however, the disclosure is not limited toany one of these and may reside in two or more of these combinedtogether. Examples are given for illustration only and not forlimitation.

What is claimed is:
 1. A stent graft comprising an elongate tubular bodyof a biocompatible graft material, the tubular body comprising a distalend and a proximal end, the tubular body comprising a proximal portionof a first selected diameter, a distal portion of a second selecteddiameter, the second selected diameter being less than the firstselected diameter and a tapered central portion between the proximalportion and the distal portion, the tubular body comprising acircumference, a notional anterior longitudinal datum line on thetubular body and a notional transverse clock face having 12 o'clock atthe notional anterior longitudinal datum line; a scalloped cut out inthe proximal portion of the tubular body, the scalloped cut out beingopen at the proximal end of the tubular body; a fenestration in theproximal portion, the fenestration being distal of the scalloped cutout; a first fenestration assembly and a second fenestration assembly inthe distal end of the tapered central portion, the scalloped cut outbeing circumferentially centered with respect to the notional transverseclock face at 12:30 o'clock, the fenestration in the proximal portionbeing circumferentially centered with respect to the notional transverseclock face at 12:00 o'clock, the first fenestration assembly beingcircumferentially centered with respect to the notional transverse clockface at 2:15 o'clock and the second fenestration assembly beingcircumferentially centered with respect to the notional transverse clockface at 10:00 o'clock.
 2. A stent graft as in claim 1 comprising aplurality of self expanding stents affixed along the tubular body.
 3. Astent graft as in claim 1 comprising an exposed zig zag self expandingstent extending from the proximal end of the proximal portion.
 4. Astent graft as in claim 1 wherein the tapered portion comprises anarcuate side wall whereby the tapered portion comprises an outer facewhich is concave.
 5. A stent graft as in claim 1 wherein the firstfenestration assembly comprises a first low profile side arm and thesecond fenestration assembly comprises a second low profile side armeach of the first and second low profile side arms comprising a proximalexternal open end.
 6. A stent graft as in claim 5 wherein the first andthe second low profile side arms each comprise a tubular side branchsealingly received into a side arm fenestration wherein an inner portionof the tubular side branch extends within the tubular body and an outerportion of the tubular side branch extends exteriorly of the tubularbody and such that the tubular side branch extends from the tubular bodyat an angle thereto.
 7. A stent graft as in claim 1 wherein each of thefirst and the second low profile side arms comprises a reinforcementstent and wherein the reinforcement stent comprises a portion of wireforming a first ring and a second ring, the second ring defining a planewhich is substantially parallel to and spaced axially apart from theplane of the first ring and at least one wire strut extending betweenthe first ring and the second ring.
 8. A stent graft as in claim 5wherein the stent graft comprises an overall length of approximately 111mm, the first selected diameter of the proximal portion being 30 mm, thesecond selected diameter of the distal portion being 20 mm, the proximalportion comprising a longitudinal length of about 39 mm, the distalportion comprising a longitudinal length of about 54 mm, the taperedportion comprising a longitudinal length of approximately 18 mm, thescalloped cut out comprising a circumferential width of about 20 mm anda longitudinal depth of about 19 mm, the fenestration comprising adiameter of 8mm and being centered at a space of 26 mm from the proximalend, external open ends of the first and second low profile side armseach being positioned at a distance of 55mm from the proximal end.
 9. Astent graft as in claim 1 wherein the proximal portion of the tubularbody comprises a proximally extending bare attachment stent and a firstand a second self expanding stent. the first and the second selfexpanding stents being spaced apart longitudinally, the tapered centralportion comprises a single self expanding stent and the distal portioncomprises a plurality of self expanding stents.
 10. A stent graft as inclaim 9 wherein each of the second stent of the proximal portion and thesingle self expanding stent of the tapered central portion comprise anasymmetric self expanding zig zag stent, each of the asymmetric selfexpanding zig zag stents comprising a plurality of struts and proximaland distal bends between the struts and a circumference and a part ofthe circumference comprising bends being spaced circumferentiallyfurther apart than others of the bends, thereby defining wider voidregions between the bends which are spaced circumferentially furtherapart.
 11. A stent graft as in claim 10 wherein the second stent of theproximal portion is positioned such that the part of the circumferencecomprising bends being spaced further apart is in an anterior region ofthe stent graft and the fenestration in the proximal portion is in awider void region.
 12. A stent graft as in claim 10 wherein the singleself expanding stent of the tapered central portion is affixed to thestent graft such that the part of the circumference comprising bendsbeing spaced further apart is in an anterior region of the stent graftand the void regions are longitudinally proximal of the first and thesecond fenestration assemblies.
 13. A stent graft as in claim 1 whereinthe tapered central portion comprises an asymmetric self expanding zigzag stent, the asymmetric self expanding zig zag stent comprising aplurality of struts and proximal and distal bends between the struts anda circumference and a part of the circumference comprising bends beingspaced circumferentially further apart than others of the bends, therebydefining wider void regions between the bends which are spacedcircumferentially further apart, the asymmetric self expanding zig zagstent being affixed to the stent graft such that the part of thecircumference comprising bends being spaced further apart is in theposterior region of the stent graft and the void regions arelongitudinally proximal of the first and the second fenestrationassemblies.
 14. A stent graft as in claim 6 wherein the tubular sidebranches are each mounted into the tapered portion by being stitched tothe tubular body, the stitching extending circumferentially anddiagonally from a proximal end of the tubular side branch to a distalend of the tubular side branch such that the tubular side branch extendsfrom the tubular body at an angle thereto.
 15. A stent graft comprisingan elongate tubular body of a biocompatible graft material, the tubularbody comprising a distal end and a proximal end, the tubular bodycomprising a proximal portion of a first selected diameter, a distalportion of a second selected diameter, the second selected diameterbeing less than the first selected diameter and a tapered centralportion between the proximal portion and the distal portion, the tubularbody comprising a circumference, a notional anterior longitudinal datumline on the tubular body and a notional transverse clock face having 12o'clock at the notional anterior longitudinal datum line; a scallopedcut out in the proximal portion of the tubular body, the scalloped cutout being open at the proximal end of the tubular body; a fenestrationin the proximal portion distal of the scalloped cut out; a first lowprofile side arm and a second low profile side arm in the distal end ofthe tapered central portion, the first and the second low profile sidearms each comprising an external open end, the tapered central portioncomprising an asymmetric self expanding zig zag stent, the asymmetricself expanding zig zag stent comprising a plurality of struts andproximal and distal bends between the struts and a circumference and apart of the circumference comprising bends being spacedcircumferentially further apart than others of the bends, therebydefining wider void regions between the bends which are spacedcircumferentially further apart, the asymmetric self expanding zig zagstent being affixed to the stent graft such that the part of thecircumference comprising bends being spaced further apart is in ananterior region of the stent graft and the void regions arelongitudinally proximal of the first and the second low profile sidearms; the scalloped cut out being circumferentially centered withrespect to the notional transverse clock face at 12:30o'clock andcomprising a circumferential width of about 20 mm and a longitudinaldepth of about 20 mm, the fenestration in the proximal portion beingcircumferentially centered with respect to the notional transverse clockface at 12:00 o'clock and comprising a diameter of 8 mm and beingcentered at a distance of about 26 mm from the proximal end, the firstlow profile side arm being circumferentially centered with respect tothe notional transverse clock face at 2:15 o'clock and the second lowprofile side arm being circumferentially centered with respect to thenotional transverse clock face at 10:00 o'clock and proximal ends ofeach being positioned at a space of 55 mm from the proximal end.